Psf2-HBD is inactivated in the absence of estradiol. A, psf2-HBD and wild type cells were serially diluted and spotted onto YE plates containing estradiol at the indicated concentrations. B, Strain P1520 (psf2-HBD:kanMX 6) was grown in EMM plus 125 mM estradiol to log phase then shifted to EMM-N (+estradiol) for 16 at 25°C. Cells were released from the block by transferring to EMM+N in the absence (left) or presence (right) of estradiol. C, As in A, except that cells were released into EMM+N in the absence of estradiol, and 125 nM estradiol was added at 4 h. D, Cell extracts were made using the TCA method from cells incubated with and without estradiol as indicated. The extracts were run on protein gels and Psf2 was detected using an antibody against the YFP tag.